1. Field of the Invention
The present invention relates to a resist pattern forming method, a thin-film pattern forming method, and a microdevice manufacturing method.
2. Related Background Art
In recent years, studies for making thin-film patterns finer have been underway in order to attain a higher density in microdevices having thin films such as thin-film magnetic heads, semiconductor devices, and MEMS devices. Its typical example is a method using a resist pattern which will be explained in the following.
First, a resist layer is formed on a thin film. This layer is exposed to light through a photomask, and is developed with an alkaline developer, so as to form a resist pattern. Finally, the thin film in the part not covered with the resist pattern is removed by dry etching or the like; or a plating layer is deposited thereon, then the resist pattern is removed, and the thin film in the part not covered with the plating layer is removed by dry etching or the like, whereby the thin-film pattern can be formed.
Though the thin-film pattern becomes finer as a gap (which will also be referred to as “trench width” in the following) in the resist pattern is made narrower, the trench width is hard to become narrower than a predetermined level because of an optical limit at the time of exposure.
On the other hand, a method known as so-called RELACS has been reported, which can further narrow the trench width in the method of forming a thin-film pattern by using a resist pattern. For example, methods disclosed in Japanese Patent Application Laid-Open Nos. H 11-204399, H6-252040, and 2004-247399 form a pattern of an acid-feedable resist layer by heating or exposure to light, applies a resin composition crosslinkable in the presence of an acid onto the pattern, and heats the composition, so as to form a crosslinked layer on the surface of the resist layer, whereby a new resist pattern having a narrower trench width made of the former resist pattern and the crosslinked layer can be formed.